Your air conditioner is likely responsible for 50 to 70 percent of your summer electricity bill in Texas, which means it is also where the largest cuts are available. This article works through the problem methodically: first the math behind AC cost per hour in Texas, then the actions ranked by realistic savings impact, then the rate-structure decisions that determine whether those actions actually show up on your bill.
This is a supporting piece in the LightCompanies “Lower Your Bill” series. The pillar article covers the full landscape of electricity cost reduction. Here the focus is AC specifically.
What Central AC Actually Costs Per Hour in Texas
Before optimizing anything, it helps to know the baseline number.
A standard central AC system in a Texas home draws between 3,000 and 5,000 watts (3 to 5 kilowatt-hours per hour of runtime). A 3-ton unit is roughly 3,500 watts; a 4-ton unit is roughly 4,500 watts. At the statewide average residential rate of approximately 14 to 16 cents per kWh in summer 2025, the math looks like this:
- 3-ton unit (3.5 kW) at 15 cents/kWh: 52 cents per hour of runtime
- 4-ton unit (4.5 kW) at 15 cents/kWh: 68 cents per hour of runtime
- 5-ton unit (5.0 kW) at 15 cents/kWh: 75 cents per hour of runtime
An AC does not run continuously. A well-functioning system in a well-insulated home might run 40 to 60 percent of the time during peak summer hours. In a poorly insulated home or during extreme heat events (days above 100°F are now routine in Dallas, Houston, and San Antonio), runtime can push to 80 to 90 percent, with the unit cycling on constantly just to hold the setpoint.
At 60 percent runtime over a 16-hour cooling day, a 4-ton unit accumulates roughly 9.6 hours of actual run time. At 68 cents per runtime hour, that is about $6.50 per day from the AC alone, or roughly $195 per month. At 80 percent runtime, the same unit costs $260 per month.
The gap between a well-tuned home and a poorly tuned one, on the same equipment and the same rate plan, is approximately $65 per month or more. That figure is the practical ceiling on what behavioral and efficiency changes can save before touching the rate plan itself.
The Six Actions That Actually Move the Number
The steps below are ordered by impact, not by ease. The harder ones tend to save more.
1. Raise the Thermostat Setpoint (and Be Precise About the Number)
Every degree you raise the setpoint reduces runtime and therefore cost. The relationship is not perfectly linear because humidity levels shift with temperature, but as a working approximation, raising your thermostat from 72°F to 76°F reduces AC runtime by roughly 12 to 16 percent in Texas summer conditions.
For the 4-ton example above, that is a runtime reduction of about 1.2 to 1.5 hours per day, saving roughly $0.80 to $1.00 daily, or $24 to $30 per month. Done alone, this is the single highest-return action because it costs nothing.
The DOE’s longstanding guidance on 78°F as the efficiency setpoint is worth noting, but 78°F is uncomfortable for many households. A practical middle ground: 74 to 75°F when home, 80°F when away, and 78°F when sleeping. Using a programmable or smart thermostat to automate this schedule removes the friction.
2. Reduce Internal Heat Gain
Your AC does not just fight outdoor heat. It fights every heat source inside the envelope: cooking, lighting, appliances, human bodies, and solar gain through windows. Reducing internal load reduces how hard the AC has to work to hold a setpoint.
High-impact actions in this category:
- Window coverings during peak sun hours. South- and west-facing windows are the primary solar gain vectors in Texas. Cellular shades or reflective blinds can reduce solar heat gain through a window by 40 to 60 percent. On a west-facing wall in Austin at 4 PM in July, this matters considerably.
- Switch remaining incandescent or older CFL bulbs to LED. Incandescent bulbs convert roughly 90 percent of their energy to heat. A 60W incandescent replaced with an 8W LED eliminates 52 watts of continuous heat load per bulb. In a home with 20 bulbs running 4 hours per evening, that is a meaningful reduction in both direct electricity cost and AC load.
- Avoid oven use during peak cooling hours. An electric oven at 375°F dumps heat into the kitchen continuously. Running it at 7 PM in July when outdoor temps are still 98°F forces the AC to handle both ambient heat and cooking heat simultaneously. Slow cookers, Instant Pots, and outdoor grilling shift the load more favorably.
3. Improve Attic Ventilation and Insulation
The attic is where most Texas homes leak the most energy. An unventilated attic in Dallas in July reaches 150 to 160°F. That heat conducts downward through inadequately insulated ceilings into conditioned space, adding continuously to the AC load.
The minimum recommended insulation level for Texas attics (climate zones 2 and 3) is R-38 to R-60. Many homes built before 2000 have R-19 or less. Upgrading from R-19 to R-38 in a 1,500-square-foot attic floor costs roughly $800 to $1,500 installed, and the savings can reach $15 to $30 per month in summer. Payback period is typically 3 to 5 years, which is reasonable for a permanent structural improvement.
Properly sealed attic bypasses (around recessed lights, top plates, and penetrations) add further benefit and often cost under $200 in materials if you do the work yourself.
4. Maintain the Equipment
An AC system that is low on refrigerant, has a dirty evaporator coil, or is running with a clogged filter works harder and longer to achieve the same cooling. A 10 to 15 percent refrigerant undercharge can reduce efficiency by 20 percent. A clogged filter reduces airflow and forces the blower motor to draw more power.
Maintenance actions that are verifiably effective:
- Replace the air filter every 1 to 3 months (not once a year). A MERV 8 filter is a reasonable balance between filtration and airflow restriction.
- Clean the outdoor condenser coils annually. Dirt and debris on the coil surface reduce heat rejection and drive up head pressure, reducing efficiency.
- Schedule a refrigerant check with an HVAC technician every 2 to 3 years or immediately if the system seems to run longer than usual to reach the setpoint.
5. Seal the Building Envelope
Conditioned air escaping through gaps in the envelope means the AC replaces that air continuously. The EPA estimates that air sealing combined with added attic insulation saves homeowners an average of 15 percent on heating and cooling costs. Common leakage points in Texas construction: recessed lighting canisters in the ceiling, gaps around electrical outlets on exterior walls, the attic hatch, and around plumbing and duct penetrations.
A blower door test, performed by a certified energy auditor, quantifies exactly how leaky a home is and identifies where the leakage is concentrated. Cost runs $200 to $400. For a home spending $250 per month on AC, even a 10 percent improvement in air sealing returns the audit cost in roughly eight to sixteen months.
6. Address Duct Losses
In many Texas homes, the duct system runs through unconditioned attic space. Ducts that are poorly insulated, disconnected at joints, or simply aging leak conditioned air into the attic rather than into the rooms being cooled. HVAC industry estimates suggest that a typical duct system loses 20 to 30 percent of conditioned air to duct leakage and conduction losses.
Duct sealing with mastic or metal tape (not standard cloth duct tape, which fails over time) and wrapping exposed ducts with R-8 insulation can recover a significant fraction of those losses. This work typically costs $500 to $1,500 for a professional duct sealing job and can reduce AC energy use by 15 to 20 percent on its own.
How Your Rate Plan Determines Whether the Savings Are Real
All of the steps above reduce AC runtime. But runtime reduction only translates directly to bill reduction if your rate plan charges on a straightforward per-kWh basis. Several Texas plan structures complicate that relationship.
Free nights or free weekends plans. If your provider offers free electricity during off-peak hours, shifting discretionary loads (laundry, dishwasher, EV charging) to those windows saves money. But free-period plans typically offset the cost with higher daytime rates. If your AC runs heavily during the daytime peak, you may pay more on a free-nights plan than on a flat rate, depending on your usage profile.
Bill credits at usage thresholds. A number of Texas plans include a bill credit (typically $30 to $50) when monthly usage exceeds a set threshold, often 1,000 or 2,000 kWh. LightCompanies has flagged this structure in 10 of the 11 plan reviews published to date as high-gimmick, because it creates an incentive to consume more electricity to qualify for the credit. If your home’s AC efficiency improvements push you below the threshold, your effective per-kWh cost can rise rather than fall. Always check the EFL (Electricity Facts Label) for the effective rate at multiple usage tiers (500, 1,000, and 2,000 kWh) before choosing a plan.
Time-of-use (TOU) plans. ERCOT’s grid stress typically peaks between 3 PM and 9 PM on summer weekdays. Several Texas providers offer TOU plans that charge premium rates during those hours and reduced rates at other times. If you can pre-cool your home before 3 PM (dropping the thermostat 2 to 3 degrees in the late morning) and let the setpoint drift up slightly during peak hours, a TOU plan can meaningfully reduce costs. If your household is home and active during peak hours and cannot tolerate a warmer setpoint, a flat-rate plan is likely a better fit.
The interaction between efficiency improvements and plan structure is why LightCompanies evaluates both dimensions in provider and plan reviews. Reducing AC runtime is necessary but not sufficient. The rate structure has to reward that reduction.
Prioritizing the Actions: A Practical Sequence
Not every household has the budget or the access (renters versus owners) to implement all six actions. Here is a practical sequence based on cost, access restrictions, and return:
| Priority | Action | Estimated Monthly Savings | Upfront Cost | Accessible to Renters |
|---|---|---|---|---|
| 1 | Thermostat schedule optimization | $20 to $40 | $0 to $30 (programmable thermostat) | Yes |
| 2 | Air filter replacement and condenser cleaning | $5 to $15 | $10 to $50/year | Usually yes |
| 3 | Window coverings (south and west) | $10 to $25 | $50 to $200 | Usually yes |
| 4 | Lighting upgrade to LED | $5 to $15 | $30 to $80 | Yes |
| 5 | Attic insulation upgrade | $15 to $30 | $800 to $1,500 | Owner only |
| 6 | Duct sealing and insulation | $15 to $40 | $500 to $1,500 | Owner only |
| 7 | Air sealing (envelope) | $10 to $30 | $200 to $600 | Owner, or with landlord approval |
Renters working through steps 1 to 4 can realistically capture $40 to $95 per month in reduced AC costs without structural changes. Owners who complete all seven steps, including plan optimization, can approach $100 to $150 per month in sustained summer savings relative to a do-nothing baseline.
A Note on Plan Selection and Provider Quality
Efficiency improvements and behavioral changes are only half of the equation. The other half is the rate structure and provider reliability. LightCompanies currently covers 34 providers under active analysis, with PUCT complaint data on file covering July through December 2025, normalized per 10,000 estimated customers. Providers with high complaint rates on billing accuracy are a risk specifically for households trying to track efficiency gains, because billing errors make it impossible to distinguish real savings from invoice mistakes.
If your current provider’s billing accuracy is questionable, the EFL math on a new plan is worth examining before investing in home efficiency improvements. The pillar article in this series covers how to read an EFL and compare plans across usage tiers.
Reducing AC electricity cost is a two-lever problem: reduce consumption, and pay a fair per-unit rate for what you do consume. Both levers need attention.